Automatic toothbrush

ABSTRACT

An automatic fluid-powered toothbrush provided with a fluid vibrator motor having a power chamber with a movable wall such as a piston or a membrane connected to the brush member for causing vibrating movement thereof. At least one fluid port is arranged in the fluid path, and a valve is arranged with each port for opening and closing same. The closed or opened condition of each valve is determined by a bistable fluid switch controlled by the fluid pressure in the power chamber. The fluid switch may have a movable switching component which acts as a valve body. An auxiliary chamber is preferably provided in constant fluid communication with the fluid supply aperture and also has a movable wall. The movable walls of the power chamber and the auxiliary chambers are coupled to one another for the transmission of movement to one another. The chambers and passages may be arranged in a plurality of plates, such as, of a plastic, which are stacked with rubber packing plates between them, parts of which may act as a diaphragm-type movable wall or as a valve body.

3,213,471 10/1965 Freeman States Patent Peter Leendert Holster;

Hendricus Franciscus Gerardus Smulders; Cornelis Johannes Theresia Potters, all of Emmasingel, Eindhoven, Netherlands [21] Appl. No. 879,844

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[72] Inventors [22] Filed Nov. 25, 1969 [45] Patented Jan. 4, 1972 [73] Assignee U.S. Philips Corporation New York, N.Y.

[32] Priority Nov. 29, 1968 [33] Netherlands [54] AUTOMATIC TOOTHBRUSH I 34- 45 Q 7 s s 37 t s ,9 g 39 3,484,885 12/1969 Deines et a1. 15/22 R FOREIGN PATENTS 1,802,838 6/1969 Germany l5/22 R Primary Examiner-Edward L. Roberts Attorney-Frank R. Trifari ABSTRACT: An automatic fluid-powered toothbrush provided with a fluid vibrator motor having a power chamber with a movable wall such as a piston or a membrane connected to the brush member for causing vibrating movement thereof. At least one fluid port is arranged in the fluid path, and a valve is arranged with each port for opening and closing same. The closed or opened condition of each valve is determined by a bistable fluid switch controlled by the fluid pressure in the power chamber. The fluid switch may have a movable switching component which acts as a valve body. An auxiliary chamber is preferably provided in constant fluid communication with the fluid supply aperture and also has a movable wall. The movable walls of the power chamber and the auxiliary chambers are coupled to one another for the transmission of movement to one another. The chambers and passages may be arranged in a plurality of plates, such as, of a plastic, which are stacked with rubber packing plates between them, parts of which may act as a diaphragm-type movable wall or as a valve body.

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l'llll PETER 1.. HOLSTfl AGEN AUTOMATIC TOOTHBIRUSII The invention relates generally to an automatic toothbrush and more particularly to such a toothbrush provided with a fluid vibrator motor having at least one chamber which acts as a power chamber having a movable wall.

US. Pat. No. 3,213,471 describes an automatic toothbrush of this kind which is equipped with a water vibrator motor. The appliance can be connected to the water supply mains by means of a hose; the energy required for the brushing action is supplied by the pressurized water of the water supply mains. The vibrator motor comprises a fluid oscillator of the type in which a fluid flow can be switched from one state to the other under the sole action of the fluid itself. The fluid oscillator is provided with two output'ducts of which one is connected to the power chamber and the other to the discharge port of the motor. Switching the fluid flow back and forth is effected by means of two control jets which each are tapped from the main flow in the output ducts by way of a feedback duct having a given resistance value and a given fluid capacity. The frequency of the oscillator depends upon its geometry and upon the pressure and the density of the fluid supplied.

A characteristic of this known automatic toothbrush is that the fluid oscillator will have a high frequency. This is due to the fact that the frequency of the oscillator is determined by the velocity at which the fluid signal propagates in the feedback passage, which velocity in a first approximation is equal to the velocity of sound in the respective fluid, in this case water. Hence, pressure pulses of very short duration are applied to the power chamber, and during these short periods only small amounts of water can flow to the power chamber.

It is an object of the invention to obviate this characteristic and the invention is characterized in that in the part of the fluid trajectory from a fluid supply port through the power chamber to a fluid discharge port, along which part the fluid always flowsin substantially the same direction during the operation of the fluid vibrator motor, at least one primary port is located which is adapted to be closed under the influence of a bistable fluid switch arranged to be controlled by the fluid pressure in the power chamber.

The term primary port is used herein to means any port which is disposed in the above-mentioned part of the trajectory of what might be termed the main flow of the fluid through the motor.

The expression a bistable fluid switch arranged to be controlled by the fluid pressure in the working chamber" is to be understood to mean: a device operating solely with fluid to the energy medium and as the information-carrying medium, the input signal to which device is the fluid pressure in the power chamber or another pressure directly related thereto, which device provides one or more output signals in the form of a fluid pressure or a displacement, which output signals can have only two values, which correspond to a logical or a 1ogical l, the invention further having the property that switching takes place solely if the input signal either exceeds a high limit or falls below a low limit, the switching action on the high limit being exceeded taking place only if the preceding switching of the switch was due to the signal falling below the low limit, and conversely the switching action on the signal falling below the low limit taking place only if the preceding switching of the switch was due to the high limit being exceeded.

It should be remarked here that for a clear understanding of the fluid vibrator motor in the automatic toothbrush according to the invention it should be kept in mind that each fluid passage has a certain resistance value, the shape and the dimensions of the flow channel being two of the factors determining this value. In the description hereinafter, when the term a fluid resistance is used, it is not intended to mean a distinct component part which acts as such a resistance.

In the automatic toothbrush according to the invention, the fluid pressure in the power chamber of the fluid vibrator motor will vary between limits which are determined by the static characteristic of the bistable fluid switch, which limits obviously must lie between the pressures under which the fluid is supplied to the motor and discharged from the motor, but which otherwise may be freely chosen. By widely spacing these limits a comparatively large power can be generated in the working chamber. V

Bistable fluid switches suited for use in the fluid vibrator motor of the automatic toothbrush according to the invention may be designed in a variety of manners and may consist or be composed of commercially available fluidic elements. An embodiment of the invention which is highly suitable for the in tended use is characterized in that the bistable fluid switch includes a switching member arranged to be moved under the influence of fluid pressure forces and at least one stop for the switching member, in which stop at least one passage terminates, the orifice of which is a switching port adapted to be closed by the switching member, the said fluid pressure forces acting at least on a projected area F l which is continuously influenced by an at least substantially constant fluid pressure, on a projected area F, located opposite F, and continuously influenced by the fluid pressure in the power chamber, and on a projected area P, which in one position of the fluid switch is influenced either by at least substantially the same fluid pressure as is F, and then lies on the same side as F l or by at least substantially the same fluid pressure as is F and then lies on the same side as F and in the other position of the fluid switch is influenced by the fluid pressure in a space which is in fluid connection with a fluid discharge aperture,

The automatic toothbrush can be compactly and simply built if according to a further embodiment the or each switching port also is a primary port.

One of the advantage of a still further embodiment of the invention is that the fluid switch is operated by the sole influence of fluid pressure forces, and this embodiment is characterized in that two stops are provided one on each side of the switching member, that F is greater than the sum of F, and F and that F lies on the same side as F In the water vibrator motor of the known automatic toothbrush one-half of the water supplied is directly discharged through one of the output passages of the fluid oscillator, namely through the passage leading to the discharge aperture. In the automatic toothbrush according to the invention an important saving in the consumption of fluid is obtainable, and also the bistable fluid switch can be given a very simple form, if according to a preferred embodiment of the invention there terminates in each of the stops a passage, the orifice in the stop situated upstream with respect to the power chamber being in fluid communication with a fluid supply aperture, and having a projected area F and the orifice in the stop situated downstream with respect to the power chamber forming a primary port in the fluid discharge trajectory of the working chamber.

In the above-mentioned known automatic toothbrush, during the time in which the power chamber is emptied the diaphragm constituting the movable wall of the working chamber is moved by a relaxing compression spring. This spring will have to exert a comparatively large force, since otherwise during the emptying period of the power chamber insufi'icient energy will be delivered to move the brush over the teeth. Further, the force exerted by the spring must show no large variations over the distance travelled by the diaphragm, so that the spring must have a comparatively level characteristic. The said requirements cannot readily be satisfied by a conventional spring in the restricted space available in an automatic toothbrush.

An embodiment of the invention obviates this difficulty and is characterized in that the fluid vibrator motor has an auxiliary chamber which is in fluid communication with a fluid supply aperture and has a movable wall having a projected area smaller than that of the power chamber, and in that the movable walls of the power chamber and of the auxiliary chamber are coupled to one another for transferring movements to one another, the movements of the coupled pair of movable walls being limited by stops.

In this embodiment the movable wall of the power chamber is moved in both directions under the influence of fluid pressure forces only. Since the fluid pressure in the auxiliary chamber is equal to that of the fluid supplied to the fluid motor, which latter pressure usually will be constant, for example will be equal to the water-supply mains pressure, the auxiliary chamber performs the function of a spring having a perfectly level characteristic. The stops for the coupled pair of movable walls are necessary in order to obtain fluid pressure variations in the power chamber which are required for controlling the bistable fluid switch. Important additional advantages are that the variation in time of the fluid pressure in the power chamber may closely approximate to the square wave shape desired for generating a high power in the available space, that it is readily possible to cause the movable walls to make a comparatively large stroke, and that variations in the fluid supply pressure do not affect the symmetrical operation of the motor. In view of the fact that the water-supply pressure may differ by several atmospheres from town to town, the last of the above properties can be regarded as important in automatic toothbrushes having water vibrator motors.

An automatic toothbrush of the said kind capable of delivering a maximum force which is independent of the direction of movement of the brush, is characterized in that the movable wall of the auxiliary chamber of the fluid vibrator motor has a projected area which is substantially one-half of that of the movable wall of the power chamber.

An embodiment which is attractive specifically in view of mass production of the automatic toothbrush is characterized in that the chambers and the passages of the fluid vibrator motor are formed in a number of stacked plates which locally are in fluid communication with one another but otherwise are insulated from one another with respect to fluid, in that the said movable walls are in the form of resilient fluid-impermeable diaphragms, and in that the switching member of the bistable fluid switch is disposed between two such diaphragms.

The invention will now be described more fully with reference to a number of embodiments, given by way of example only, and to the partly schematic drawings, in which:

FIG. 1 is a schematic side elevation of an automatic toothbrush according to the invention equipped with a water vibrator motor,

FIG. 2 is a graph showing the variation of the pressure in the power chamber of the water vibrator motor of the automatic toothbrush shown in FIG. 1 without an external load,

FIG. 3 schematically shows a bistable water switch,

FIG. 4 shows the locations of the areas F F and F in the switching member ofthe water switch of FIG. 3,

FIG. 5 shows the static characteristic of the water switch of FlG. 3,

FIG. 6 is a schematic diagram of a water vibrator motor in which the water switch of FIG. 3 is used,

FIG. 7 is a modified embodiment of the schematic diagram of FIG. 6 employing a water switch which is operated solely by the influence of water pressure forces,

FIG. 8 shows the static characteristic of the water switch used in the motor of FIG. 7,

FlG. 9 is a schematic diagram of a water vibrator motor having two primary ports and an auxiliary chamber,

FIG. 10 is a graph of the variation of the pressure in the power chamber of the symmetrically loaded water vibrator motor shown in FIG. 9, and finally,

FlG. 11 shows a practical embodiment of the automatic toothbrush of FIG. 1 in part top plan view and part cross-sectional view.

An automatic toothbrush 1 shown schematically in FIG. 1 has a part 2 which serves as the handle and on which, as is usual in automatic toothbrushes, a brush 3 proper is removably provided. The automatic toothbrush shown is intended to be driven by water from the water-supply mains and for this purpose it is provided with a water-supply hose 4 and a water-discharge hose 5. For the sake of clarity, in the drawing the direction of flow of the water towards the toothbrush and that away from it are indicated by arrows.

A water piston motor is shown schematically in the handle 2. A power chamber 6 has a movable wall in the form of a piston 7 which is connected to a connecting rod 8. The motor has a single primary port in a stop valve shown symbolically by 9. The primary port can be closed under the influence of a bistable water switch 10 which is controllable by the water pressure in the power chamber and is shown symbolically as a rectangle enclosing its static characteristic. Broken lines II and 12 represent the input and output signals, respectively, of the water switch 10. The piston 7 is unilaterally loaded by a compression spring 13. Water resistances are symbolically shown at 14 and 15. The connecting rod 8 through a crank pin 16 and an eccentric l7 drives a shaft l8 rotatably mounted in the handle 2, so that in operation the brush 3 is given an oscillating reciprocating movement.

The operation of the motor shown in FIG. I will be described more fully with reference to the graph of the pressure variation in the power chamber with unloaded motor (FIG. 2), time being plotted along the horizontal axis and the pressure in the working chamber along the vertical axis. At t, a cycle begins; at this instant the stop valve 9 is operated under the influence of the water switch 10 so that the primary port opens and water can flow from the supply hose 4 through the valve 9 and the resistance 14 to the power chamber 6. However, simultaneously water from the power chamber can flow through the resistance 15 to the discharge hose 5, but the re sistances l4 and 15 are chosen so that the pressure in the power chamber 6 can rise in order to move the piston against the force of the compression spring 13. The pressure in the power chamber will continue to rise in accordance with the spring characteristic of the spring 13 until a an instant 1 a pressure is reached which is indicated by P At this instant the switch 10 changes state and the valve 9 is operated so that the primary port is closed. The water contained in the power chamber 6 now is expelled from this chamber by the spring 13 and flows away to the atmosphere through the resistance 15 and the discharge hose 5. The piston 7 returns to its starting position, and the pressure in the power chamber 6 falls until at an instant I; the pressure has fallen to a value shown by P,, in the graph. At this instant the bistable water switch 10 again changes state so that the stop valve 9 is again operated, and the cycle is repeated.

FIG. 3 shows schematically a bistable water switch 10 with its connections. it comprises a switching member 19 and a stop 20 for the switching member, a passage 2] terminating in this stop. The orifice 22 of this passage can be closed by the switching member 19. The switching member 19 is arranged to move in the enclosure 23 and seals the spaces above and beneath it from one another. Above the switching member 19 a compression spring 24 is disposed. A passage 25 is connected to the power chamber 6. The space remaining beneath the switching member 19 and around the stop 20 when the switching member bears on the stop is connected to the discharge hose 5 of the motor through passages 26 and 28 and consequently to the atmosphere through resistances R and R These resistances form a fluid pressure equivalent of an electric voltage divider, passage 27 is connected between R, and R The water pressure in the passage 27 is the output signal of the switch and is designated by 11,; the pressure in the passage 21 is equal to the pressure under which the water is supplied to the motor, i.e., the supply pressure of the motor. This latter pressure is designated by P, and may be regarded as constant in practice. The pressure in the passage 25 is equal to the pressure p in the power chamber. The pressures in the passages 21 and 25 may alternatively be derived from p,, and p through voltage fluid pressure dividers.

FIG. 4 shows that the area F on the lower surface of the switching member 19 is equal to the projected area of the ori free 22 in the stop 20. F is the upper surface area of the switching member 19 and F is the lower surface area decreased by F,. Both in the condition in which the orifice 22 is closed and in the condition in which it is open, the area l", is influenced by the supply pressure p and hence is continuously influenced by a constant fluid pressure. The area F is continuously influenced by the water pressure in the power chamber 6, and the area F in the condition in which the orifice 22 is not closed by the switch member 19 is influenced by the same or substantially the same water pressure as is F,, namely the supply pressure, and in the other condition is influenced by the water pressure in the space around the stop 20 and under the switch member 19, which space is connected to the water discharge hose 5 of the motor through the passages 26 and 28.

The operation of the water switch will now be discussed with reference to the static characteristic shown in FIG. 5. In the position shown in FIG. 1, i.e., the position in which the orifree 22 is not closed, there will be in the passage 27, assuming this passage not to be loaded, a water pressure pa 1 2 pv The switch member 19 will only move downward when the pressure in the power chamber has reached a value p, such that the downward force p F -l-K where K, is the force of the spring, exceeds the upward force p,,(F,+F In this case the switch member 19 is urged onto the stop 20, whereupon F continues to be influenced by P, but F is influenced by the atmospheric pressure 12 Thus, the upward force exerted on the switch member is reduced to the value p, F,, and the switch member will only move again when the pressure in the power chamber has fallen to so low a pressure p that the upward force p, F, exceeds the downward force p F,+I(,,.

In view of the small movements which the switch member 19 performs in practice, in the above discussion K, has been assumed to be constant and the pressures referred to are excess pressures above atmospheric pressure.

The output signal p, of the water switch of FIG. 3 can be used 'to energize the stop valve 9 (FIG. 1). Another possibility is to use the movements of the switch member 19 for this purpose. FIG. 6 shows a use of the water switch of FIG. 3 which results in a very compact and simple construction of the water motor in that the switch port 22 is also used as a primary port. In FIG. 6, corresponding passages have been designated by the same numerals as in FIG. 3.

FIG. 7 shows the water motor of FIG. 6 with the difference that the water switch 10 is not equipped with a compression spring 24, since it is operated by the sole influence of water pressure forces. Further, in addition to the stop 20 there is a second stop 29, and F is greater than F,+F;,.

FIG. 8 shows the static characteristic of the water switch 10 of FIG. 7, and just as in FIG. p, is the water pressure in the passage 26. Owing to the coupling of the passage 26 to the power chamber 6 of the motor the extreme values of p, will be equal to the extreme values p, and p, of the water pressure p, in the power chamber. The width of the static characteristic is shown in the drawing, namely F; (Ft-F3) The pressures indicated are excess pressures above atmospheric pressure. To generate a maximum power in the power chamber 6 the water pressure in the power chamber must be variable within the widest possible limits, so that F must be small. In FIG. 7 in principle it would be possible to interchange the connection of the passages 20 and 26 to the water switch 10, but it would than be more difficult to make the area F 1 small. Further it should be noted that p cannot be greater than so that The passage 30 communicates with the atmosphere and serves to conduct away any leakage water and to exhaust the air from the space 31, which contributes to a short response time of the water switch.

FIG. 9 shows a water motor which in several points differs from that shown in FIG. 7. The stop 29 of the water switch 10 is provided with a second primary port 32, which lies in the water discharge trajectory of the power member. The primary ports 22 and 32 are alternately opened and closed by the switch member 19. The advantage of the primary port 32 is that during the filling of the power chamber 6 no water can directly flow from the supply hose 4 through the primary port 22 to the discharge hose 5; hence, the water consumption is reduced. Further, the maximum water pressure p, to be reached in the power chamber 6 is no longer detennined by the ratio between the water resistances R and R,, but p, can now become equal to the supply pressure p,,, which means that a larger power can be generated in the power chamber than is possible in the motor of FIG. 7. In addition, the width of the static characteristic of the water switch can be increased:- when the projected area of the primary port 32 is designated F, the switching member 19 has two areas on its upper surface, namely F and F F being influenced by the water pressure in the power chamber when the switch part is in its lower position, and by the atmospheric pressure when the switch member is in its upper position. As a result, the lowest water pressure p, to be achieved in the power chamber is reduced to Thus, it is found that, unlike F F, need not be small; hence, an interchange of the passages 25 and 33 in FIG. 2 does not involve specific disadvantages.

In contradistinction to the water motor shown in FIG. 7, the water motor of FIG. 9 is provided with an auxiliary space 34 which through a passage 35 is connected to the water-supply hose, so that the supply pressure p, permanently prevails in the auxiliary chamber 34. The auxiliary chamber has a movable wall the projected area of which is smaller than that of the power chamber 6 and is equal to the area of the lower surface of the piston 7 less the cross-sectional area of the connecting rod 8. Thus, in the case shown both movable walls are constituted by the piston 7, so that they are coupled to one another with respect to the transfer of movements to one another. The movements of the piston 7 are limited by two stops 36 and 37.

FIG. 10 shows the pressure variation in the power chamber of the motor shown in FIG. 9. At the instant t, the switch member 19 moves upwards so that substantially simultaneously the primary port 22 is opened and the primary port 32 is closed. The piston 7 remains pressed against the stop 36 until the water pressure has sufficiently risen to move the piston against the load and against the force exerted on the piston by the water in the auxiliary chamber 34. At the instant I, this pressure, which is designated 12,, has been reached. It will be readily appreciated that the time interval t,-t,, inter alia owing to the incompressibility of water, will be extremely short. At the instant I, the piston starts moving and, assuming the load to be constant, the pressure in the power chamber will no longer change until, at the instant t the piston engages the stop 37. Thereupon the pressure will rise rapidly until at the instant t the pressure p, is reached, to which the bistable water switch it) responds by changing its state. The primary port 22 is closed and the primary port 32 is opened. The piston 7 remains pressed against the stop 37 until the water pressure in the power chamber has fallen to the value p,,,,, at which pressure the water pressure in the auxiliary chamber 34 is capable of moving the piston against the load and against the force exerted on the piston by the water in the power chamber. The time interval t t also will be short. Again the pressure in the power chamber remains constant, assuming the load to be constant. until at the instant I; the piston again strikes the stop 36 and subsequently rapidly descends, until at the instant t the value p, is reached, the water switch 10 again changes state and the cycle is repeated. The time interval 1 -2, also is short, so that compared with the total cycle time t t-, the time intervals during which the piston 7 does not move and hence does no work are small. Consequently, the pressure variation in the power chamber approximates the the square wave form desired for a maximum generated power.

The connecting rod 8 of the motor of FIG. 9 has a cross-sectional area such that the movable wall of the auxiliary chamber 34 has a projected area which is substantially onehalf of that of the movable wall of the power chamber 6. Thus, the motor is capable of delivering the same maximum power in both directions, which naturally is important in an automatic toothbrush. This property of the motor of FIG. 9 can also be found in FIG. 10; the graph of the pressure variation in the power chamber has been pictured on the assumption that the motor load is equal in both directions and is nearly a maximum, in which case the pressures occurring in the power chamber are p and p,,,,, which are situated symmetrically with respect to the pressure law -i12 which pressure can be made practically equal to hp,

A particular feature of the automatic toothbrush according to the invention is that the water vibrator motor cannot be stopped by externally restricting the movements of the movable wall of the working chamber. If, for example, in the case of the motor of FIG. 9 an obstacle is placed in the path of the connecting rod 8, this obstacle will only act as a stop, limiting the movements of the movable wall, i.e., the piston 7. The motor will continue operating, but with a shortened stroke and a shorter cycle time. The motor can only be stopped by preventing all movement of the piston 7.

FIG. 11 shows a practical embodiment of the toothbrush of FIG. 1 in part top plan view, part cross-sectional view. The chambers and the passages of the water vibrator motor have been formed in a number of stacked plates 38 to 42, which are made of a water-impermeable substance, i.e., a nonporous synthetic material, and are locally in water communication with one another but otherwise are insulated from one another. The movable walls of the power chamber 6 and of the auxiliary chambers 34 are constituted by resilient water-impermeable diaphragms which form part of water-insulating rubber sheets 43 and 44. The switch member 19 also is disposed between two such diaphragrns.

The particular positioning of the power chamber 6 and the auxiliary chamber 34 and the use of diaphragms result in an extremely compact construction in which no sealing problems crop up. The piston 7, which here does not have a connecting rod, directly drives the brush 3 for which purpose the crank pin 16 can move in a slot-shaped recess 45. Contrary to what is the case in FIG. I, the connections for the water supply hose and the water discharge hose, which obviously may, if desired, by united to form a single hose, are located within the handle 2; a plug-shaped connecting member for the water-supply hose is indicated at 46.

It should be noted that the term switch member" used so far must be taken in a broad sense and includes embodiments in which the space 31 does not contain a single discrete member 19 but, for example, one or more members connected to the diaphragms or several discrete members, and even embodiments in which the space 31 is filled with a liquid or a gas.

FIG. 11 clearly shows that the water vibrator motor can readily be accommodated in the handle 2 of the toothbrush and is constructionally simple. It is important, especially in view of mass production, that for satisfactory operation of the motor it should not be necessary for the various components to be manufactured within very close dimensional tolerances, and the absence of this requirement will obviously reduce manufacturing cost.

With an automatic toothbnish designed according to FIG. 11 satisfactory results were obtained; the frequency of the oscillating movement of the brush 3 was about 25 Hz. and the force generated at the brush was amply sufiicient for thoroughly cleaning the teeth. The dimensions of the handle were smaller than those of some commercially available electric automatic toothbrushes.

What is claimed is:

l. A vibrating fluid-powered toothbrush comprising a handle, a brush member detachably connected to said handle and arranged for vibrating motion with respect thereto, a fluid vibrator motor housed within said handle for driving said brush, said motor comprising a power chamber, a movable wall bounding one side of said chamber, fluid-supply port for supplying fluid under pressure to said handle, a fluid-discharge port for discharging fluid from said toothbrush, a fluid path connecting said supply port to the chamber of said motor and the chamber with said discharge port, a first primary port arranged in the fluid path, a bistable fluid switch the operation of which being activated by the pressure prevailing in said power chamber, a valve arranged for opening and closing said primary port, said switch arranged for controlling the operation of said valve, and means connecting said movable wall to said brush for causing oscillatory vibrating motion thereof.

2. The vibrating fluid-powered toothbrush according to claim 1 wherein said bistable fluid switch comprises a movable switching member adapted to move under the influence of fluid pressure forces and further comprising at least one stop for said switching member, at least one passage terminating in said stop forming a switch port arranged to be closed by said switching member, said fluid pressure forces acting on at least a first projected area (F,) of said switching member, substantially constant fluid pressure continuously acting on said first projected area, said fluid pressure forces also acting on a second projected area (F located opposite said first projected area and being continuously influenced by the fluid pressure in said chamber, and upon a third projected area (F which in one position of the fluid switch is subjected either to at east substantially the same fluid pressure as is exerted on said first projected area, in which case it is located on the same side of said first projected area, or to at least substantially the same fluid pressure as is exerted on said second projected area, in which case, it is located on the same side thereof, and in the other position of the fluid switch is subjected to the fluid pressure in a space being in fluid communication with a fluid discharge aperture.

3. The vibrating fluid-powered toothbrush according to claim 2 wherein said switch port is a primary port.

4. The vibrating fluid-powered toothbrush according to claim 3 further comprising two stops arranged in said bistable switch for said switching member and wherein said second projected area is greater than the sum of said first and third projected areas, and wherein said third projected area is located on the same side of said switching member as is said first projected area.

5. The vibrating fluid-powered toothbrush according to claim 4 further comprising a fluid passageway in said stops of said bistable switch, one of said stops being located upstream in the fluid path with respect to said power chamber and the other stop being located downstream with respect thereto, the terminating orifice of the passageway in the stop located upstream being in fluid communication with a supply aperture and having an area equal to said first projected area, and the terminating orifice of the passageway in the stop located downstream forming a primary port in the fluid discharge path of the power chamber.

6. The vibrating fluid-powered toothbrush according to claim 5 further comprising an auxiliary chamber in fluid com munication with the fluid supply port and having a movable wall with a projected area less than the projected area of the movable wall of said power chamber, means coupling the movable wall of said auxiliary chamber with the movable wall of said power chamber for transferring movement of one to the other, and a pair of stops arranged for limiting the movement of the coupled pair of movable walls.

7. The vibrating fluid-powered toothbrush according to claim 6 wherein the projected area of the movable wall of the auxiliary chamber is approximately one-half of the projected area of the movable wall of the power chamber.

8. The vibrating fluid-powered toothbrush according to claim 6 wherein the chambers and passages of the fluid vibrator motor are defined within a plurality of stacked plates in local relative fluid communication and otherwise insulated for fluid from one another and are made of a material impermea- 

1. A vibrating fluid-powered toothbrush comprIsing a handle, a brush member detachably connected to said handle and arranged for vibrating motion with respect thereto, a fluid vibrator motor housed within said handle for driving said brush, said motor comprising a power chamber, a movable wall bounding one side of said chamber, fluid-supply port for supplying fluid under pressure to said handle, a fluid-discharge port for discharging fluid from said toothbrush, a fluid path connecting said supply port to the chamber of said motor and the chamber with said discharge port, a first primary port arranged in the fluid path, a bistable fluid switch the operation of which being activated by the pressure prevailing in said power chamber, a valve arranged for opening and closing said primary port, said switch arranged for controlling the operation of said valve, and means connecting said movable wall to said brush for causing oscillatory vibrating motion thereof.
 2. The vibrating fluid-powered toothbrush according to claim 1 wherein said bistable fluid switch comprises a movable switching member adapted to move under the influence of fluid pressure forces and further comprising at least one stop for said switching member, at least one passage terminating in said stop forming a switch port arranged to be closed by said switching member, said fluid pressure forces acting on at least a first projected area (F1) of said switching member, substantially constant fluid pressure continuously acting on said first projected area, said fluid pressure forces also acting on a second projected area (F2) located opposite said first projected area and being continuously influenced by the fluid pressure in said chamber, and upon a third projected area (F3), which in one position of the fluid switch is subjected either to at east substantially the same fluid pressure as is exerted on said first projected area, in which case it is located on the same side of said first projected area, or to at least substantially the same fluid pressure as is exerted on said second projected area, in which case, it is located on the same side thereof, and in the other position of the fluid switch is subjected to the fluid pressure in a space being in fluid communication with a fluid discharge aperture.
 3. The vibrating fluid-powered toothbrush according to claim 2 wherein said switch port is a primary port.
 4. The vibrating fluid-powered toothbrush according to claim 3 further comprising two stops arranged in said bistable switch for said switching member and wherein said second projected area is greater than the sum of said first and third projected areas, and wherein said third projected area is located on the same side of said switching member as is said first projected area.
 5. The vibrating fluid-powered toothbrush according to claim 4 further comprising a fluid passageway in said stops of said bistable switch, one of said stops being located upstream in the fluid path with respect to said power chamber and the other stop being located downstream with respect thereto, the terminating orifice of the passageway in the stop located upstream being in fluid communication with a supply aperture and having an area equal to said first projected area, and the terminating orifice of the passageway in the stop located downstream forming a primary port in the fluid discharge path of the power chamber.
 6. The vibrating fluid-powered toothbrush according to claim 5 further comprising an auxiliary chamber in fluid communication with the fluid supply port and having a movable wall with a projected area less than the projected area of the movable wall of said power chamber, means coupling the movable wall of said auxiliary chamber with the movable wall of said power chamber for transferring movement of one to the other, and a pair of stops arranged for limiting the movement of the coupled pair of movable walls.
 7. The vibrating fluid-powered toothbrush according to claim 6 wherein the projected area of the movable wall of the auxiLiary chamber is approximately one-half of the projected area of the movable wall of the power chamber.
 8. The vibrating fluid-powered toothbrush according to claim 6 wherein the chambers and passages of the fluid vibrator motor are defined within a plurality of stacked plates in local relative fluid communication and otherwise insulated for fluid from one another and are made of a material impermeable to fluid, and wherein the movable walls of said power chamber and of said auxiliary chamber are formed by resilient diaphragms which are impermeable to fluid, and wherein said switch member of the bistable fluid switch is disposed between two such diaphragms. 